Digital Versatile Disc (DVD) and Digital Video Broadcast (DVB) data decoders are well known. A conventional DVD/DVB decoder system includes a central processing unit, a stream demultiplexer, an audio decoder, a video decoder, a memory controller, an MPEG system timer, a video output processor and an audio output processor.
Conventional DVD/DVB decoder systems have many disadvantages. First, they typically include two separate depacketizers; an audio depacketizer coupled to the audio decoder for depacketizing audio data, and a video depacketizer coupled to the video decoder for depacketizing video data, leading to duplication of many tasks. Therefore, such systems are not cost effective.
Second, the Central Processing Unit (CPU) of conventional DVD/DVB systems is frequently interrupted, requiring the CPU to temporarily abandon its existing tasks to service the interrupts, leading to inefficient utilization of the CPU. Furthermore, because the interrupts are frequent and not synchronized to a common event, such systems must meet strict and inflexible timing requirements. Moreover, in such systems, because the CPU typically demultiplexes the stream data in addition to handling many other tasks, it must be very powerful and hence relatively expensive.
Third, the Packetized Elementary Stream (PES) data supplied to the audio and the video decoders of conventional DVD/DVB systems typically includes a time stamp which must be stripped off before the data is decoded, resulting in processing inefficiencies.